Color electrophoretic display device and method for manufacturing the same

ABSTRACT

According to an embodiment of the present invention, a method for manufacturing a color electrophoretic display device includes forming a thin film transistor (TFT) array substrate including a display region, wherein a plurality of pixel regions is defined in a matrix, and alignment keys are provided at the outside of the display region, forming an electrophoretic layer including a micro capsule layer formed so as to correspond to the display region of the TFT array substrate, and forming a color filter layer on an outer surface of the electrophoretic layer using the alignment keys so as to correspond to the respective pixel regions of the display region.

This application is a divisional of application Ser. No. 12/645,331filed on Dec. 22, 2009 now U.S. Pat. No. 7,982,942, which claims thebenefit of Korean Patent Application No. 10-2008-0132004, filed on Dec.23, 2008, all of these applications are hereby incorporated by referenceas if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrophoretic display device, andmore particularly, to a color electrophoretic display device with acolor filter layer, which is formed in a droplet state on a rear surfaceof an electronic ink film through surface treatment so as to be capableof adjusting density of droplets in pixels and achieving correctalignment, and a method for manufacturing the same.

2. Discussion of the Related Art

An electrophoretic display device (EPD) is one of flat panel displaydevice used in E-books, and includes two display panels, on whichelectrodes for forming an electric field are formed, and micro capsulesformed between the two display panels and containing electronic inkhaving black and white pigment particles respectively charged withpositive and negative polarities.

The electrophoretic display device generates a potential difference atboth ends of two electrodes opposite to each other by applying voltageto the two electrodes, and thus respectively moving the black and whitepigment particles charged with positive and negative polarities to theelectrodes having the opposite polarities, thereby displaying an image.

Such an electrophoretic display device has high reflectivity andcontrast ratio and no dependence on a viewing angle, differing from aliquid crystal display device, and thus has advantages in that itdisplays an image in a comfortable mood like paper. Further, theelectrophoretic display device has a bistable property between black andwhite, and thus maintains the image without continuous application ofvoltage, thereby reducing power consumption. Moreover, theelectrophoretic display device does not require a polarization plate, analignment film, and liquid crystals, and thus is advantageous in termsof price competitiveness.

The above electrophoretic display device and a color filter substratedisposed thereon form a color electrophoretic display device, which iscapable of displaying colors.

Hereinafter, a conventional color electrophoretic display device will bedescribed with reference to the accompanying drawings.

FIG. 1 is a longitudinal-sectional view illustrating the conventionalcolor electrophoretic display device.

As shown in FIG. 1, the conventional color electrophoretic displaydevice 100 usually includes a thin film transistor (TFT) array substrate50, an electronic ink film 60, and a color filter substrate 70.

Here, the TFT array substrate 50 includes a first metal foil 12, such assteel use stainless (SUS) foil, formed on a glass substrate 10 tore-emit light emitted from the electronic ink film 60 toward an incidentsurface, and TFTs 13 formed on the first metal foil 12 to be drivenaccording to respective pixels. The thin film transistor array substrate50 further includes a second metal foil 14 formed on the rear surface ofthe glass substrate 10.

The electronic ink film 60 includes a micro capsule layer 25, whichcontains black and white pigment particles respectively charged withpositive and negative polarities such that the black and white pigmentparticles are arranged in a designated direction through application ofvoltage thereto, formed on a transparent conductive film 20.

The color filter substrate 70 includes a first plastic film 32 formed ona glass substrate 30, and color filters 34 having designated colorsformed in respective pixels on the first plastic film 32. The colorfilter substrate 70 further includes a second plastic film 31 forprotection formed on the rear surface of the glass substrate 30.

Thereafter, a first adhesive layer 21 and a second adhesive layer 22 arerespectively formed on the rear surface of the transparent conductivefilm 20 and on the micro capsule layer 25, and the color filtersubstrate 70 and the TFT array substrate 50 are respectively bonded tothe electronic ink film 60 through the first adhesive layer 21 and thesecond adhesive layer 22, thereby forming the color electrophoreticdisplay device 100.

In this case, in order to slim the device 100, after the bondingprocess, the glass substrate 30 and the second plastic film 31 of thecolor filter substrate 70 and the glass substrate 10 and the secondmetal foil 14 of the TFT array substrate 50 may be omitted.

However, in the conventional color electrophoretic display device 100obtained by bonding the three panels, since the three panels areseparately formed and then are bonded to each other by the bondingprocess carried out on both surfaces of the electronic ink film 60, adetaching process carried out, if misalignment among the three panelsoccurs, causes damage to the expensive electronic ink film 60, andthereby lowers image quality.

The above-described conventional color electrophoretic display devicehas several problems, as follows.

Since the conventional color electrophoretic display device is obtainedby bonding the TFT array substrate and the color filter substrate toupper and lower surfaces of the electronic ink film through therespective adhesive layers, misalignment among the three panels mayeasily occur, and thereby causes damage to the expensive electronic inkfilm during re-working.

Subsequently, if misalignment remains, correct image display is notachieved, and if the electronic ink film is damaged, image quality at adamaged region is lowered.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a colorelectrophoretic display device and a method for manufacturing the same.

One object of the present invention is to provide a colorelectrophoretic display device with a color filter layer, which isformed in a droplet state on a rear surface of an electronic ink filmthrough surface treatment so as to be capable of adjusting density ofdroplets in pixels and achieving correct alignment, and a method formanufacturing the same.

To achieve this object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for manufacturing a color electrophoretic display device includesforming a thin film transistor (TFT) array substrate including a displayregion, in which a plurality of pixel regions are defined in a matrix,and alignment keys provided at the outside of the display region,forming an electrophoretic layer including a micro capsule layer formedso as to correspond to the display region of the TFT array substrate,and forming a color filter layer on the electrophoretic layer using thealignment keys so as to correspond to the respective pixel regions ofthe display region.

The formation of the color filter layer may include carrying outhydrophobic treatment of a surface of the electrophoretic layer, andspraying color droplets expressing a plurality of colors onto thesurface of the electrophoretic layer, upon which the hydrophobictreatment is carried out, through a nozzle of an ink-jet printing devicesuch that color droplets expressing one color are formed in one pixelregion.

The hydrophobic treatment may be achieved by carrying out plasmatreatment on the surface of the electrophoretic layer, on which themicro capsule layer is not formed, through gas of any one of SF₆ and CF₄or a combination thereof.

The formation of the color filter layer may include forming an adhesivelayer on a surface of the electrophoretic layer, on which the microcapsule layer is not formed, and preparing color droplets expressing aplurality of colors, and then spraying the color droplets onto theadhesive layer using surface roughness of the adhesive layer such thatcolor droplets expressing one color are formed in one pixel region.

The method, may further include, after the formation of the colordroplets expressing one color in one pixel region, hardening the colordroplets by applying heat to the color droplets.

The method may further include forming a protective sheet on the colordroplets.

The method may further include sealing the side surface of theelectrophoretic layer so as to protect the electrophoretic layer.

The color droplets may be formed in an island type, an overlap type, oran island-overlap combination type by adjusting the amount of the colordroplets formed in the respective regions.

The color filter layer is formed in a stripe type of red, green, andblue color filters, or is formed in a quad type of red, green, blue, andwhite color filters.

In another aspect of the present invention, a color electrophoreticdisplay device includes a thin film transistor (TFT) array substrateincluding a display region, in which a plurality of pixel regions aredefined in a matrix, and alignment keys provided at the outside of thedisplay region, an electrophoretic layer including a micro capsule layerformed so as to correspond to the display region of the TFT arraysubstrate, and a color filter layer formed on a surface of theelectrophoretic layer, on which the micro capsule layer is not formed,and including a plurality of color droplets expressing different colorscorresponding to the respective pixel regions of the display region.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a longitudinal-sectional view illustrating a conventionalcolor electrophoretic display device;

FIGS. 2A to 2C are plan views illustrating a TFT substrate, anelectronic ink film, and a color filter layer during a process formanufacturing a color electrophoretic display device in accordance witha first embodiment of the present invention;

FIGS. 3A to 3C are longitudinal-sectional views respectivelycorresponding to FIGS. 2A to 2C;

FIGS. 4A to 4E are longitudinal-sectional views illustrating a processfor manufacturing the TFT substrate of the color electrophoretic displaydevice in accordance with the present invention;

FIG. 5 is a plan view illustrating a stripe-type color filter layer inthe color electrophoretic display device in accordance with the presentinvention;

FIGS. 6A and 6B are enlarged plan views respectively illustratingexamples of the color filter layer of FIG. 5 in accordance with thefirst embodiment of the present invention and a modified embodimentthereof;

FIGS. 7A to 7C are longitudinal-sectional views illustrating a methodfor forming the color filter layer of the color electrophoretic displaydevice in accordance with the present invention;

FIGS. 8A to 8C are plan views illustrating a process for manufacturing acolor electrophoretic display device in accordance with a secondembodiment of the present invention;

FIG. 9 is a plan view illustrating a quad-type color filter layer in thecolor electrophoretic display device in accordance with the presentinvention;

FIGS. 10A ad 10B are enlarged plan views respectively illustratingexamples of the color filter layer of FIG. 9 in accordance with thesecond embodiment of the present invention and a modified embodimentthereof; and

FIGS. 11A to 11C are photographs of droplets observed after formation ofthe color filter layer in the color electrophoretic display device inaccordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, with reference to the accompanying drawings, a colorelectrophoretic display device in accordance with the present inventionand a method for manufacturing the same will be described in detail.

FIGS. 2A to 2C are plan views illustrating a TFT substrate, anelectronic ink film, and a color filter layer during a process formanufacturing a color electrophoretic display device in accordance witha first embodiment of the present invention, and FIGS. 3A to 3C arelongitudinal-sectional views respectively corresponding to FIGS. 2A to2C.

In order to manufacture the color electrophoretic display device inaccordance with the first embodiment of the present invention, as shownin FIGS. 2A and 3A, a TFT array mother substrate 200 is first prepared.Here, together with TFTs 220, alignment keys 210 to sense a position ofa color filter layer are formed at the edge of the TFT array mothersubstrate 200.

Each of the TFTs 220 includes a gate electrode 221 a formed in adesignated region on the TFT array mother substrate 200, a gateinsulating film 227 formed over the entire surface of the substrate 220including the gate electrode 221 a, an island-type semiconductor layer223: 223 a, 223 b formed on the gate insulating film 227 to cover thegate electrode 221 a, and a source electrode 224 a and a drain electrode224 b formed at both sides of the semiconductor layer 223. Here, thesemiconductor layer 223 is a structure obtained by stacking an amorphoussilicon layer 223 a and an impurity layer 223 b, and some parts ofthicknesses of the impurity layer 223 b and the amorphous silicon layer223 a are removed between the source electrode 224 a and the drainelectrode 224 b.

If the TFT array mother substrate 200 is made of a metal foil, such as aSUS foil, an insulting film 226 for insulation, such as an inorganicfilm or an organic film, is interposed between the TFT array mothersubstrate 200 and the gate electrode 221 a.

A passivation film 228 is formed over the entire surface of the gateinsulating film 227 including the source and drain electrodes 224 a and224 b, a passivation film hole is formed by removing a designated regionof the passivation film 228 on the upper surface of the drain electrode224 b, and a pixel electrode 225 is connected to the drain electrode 224b through the passivation film hole.

Here, the alignment keys 210 are formed in an edge region of the TFTarray mother substrate 200 except for a display region 255, and may beformed together with TFTs or pixel electrodes during a TFT formingprocess or a pixel electrode forming process.

Non-described reference numeral 250 represents a pad region at the edgeof the display region 255. The alignment keys 210 may be formed in anyplace at the outside of the display region 255 and the outside of thepad region 250. In this case, the alignment keys 210 may be removedduring a subsequent scribing process to cut the TFT array mothersubstrate 200 into unit panels, or may remain in some regions at theoutsides of the unit panels.

Thereafter, as shown in FIGS. 2B and 3B, an electrophoretic layer 350including a micro capsule layer 310 on a substrate 300 is prepared, andis laminated on the TFT array mother substrate 200 such that the microcapsule layer 310 is opposite to the display region 255 of the TFT arraymother substrate 200. In this case, the electrophoretic layer 350 may bethinned so as to have a thickness of less than several tens of μm, andthus the thinned electrophoretic layer 350 including the micro capsulelayer 310 is bonded onto the TFT array mother substrate 200 includingthe TFTs 220 and pixel electrodes (not shown).

In this case, the substrate 300 may be made of a transparent electrode,or may be formed by carrying out a transparent conductive film treatmenton a surface, corresponding to the micro capsule layer 310, on atransparent film.

As shown in FIGS. 2C and 3C, a color filter layer 450 is formed bycarrying out hydrophobic treatment on the surface of the substrate 300and then dotting red, green, and blue pigment materials, or anadditional white pigment material on the surface of the substrate 300using an ink-jet method.

In this case, the pigment materials are not mixed with each other, andare present in a droplet state on the surface of the substrate 300.

Here, dotting of the red, green, and blue pigment materials (or thewhite pigment material) may be individually carried out according todifferent colors, or may be carried out in only one process using nozzlespray holes of the involved pigment materials corresponding to differentregions.

Thereafter, a protective sheet 400 to protect the color filter layer 450is formed.

Hereinafter, manufacture of the TFT array mother substrate will bedescribed in detail.

FIGS. 4A to 4E are longitudinal-sectional views illustrating a processfor manufacturing the TFT substrate of the color electrophoretic displaydevice in accordance with the present invention.

As shown in FIG. 4A, the insulating film 226 is deposited on the mothersubstrate 200.

Thereafter, gate electrodes 221 a, first storage electrodes 231, andgate pad metals 241 are formed in designated regions by depositing ametal material layer, made of Mo/AlNd or Cu/Ti alloy, on the insulatingfilm 226, and then selectively removing the metal material layer.

Thereafter, as shown in FIG. 4B, the gate insulating film 227 is formedover the entire surface of the substrate 200 including the gateelectrodes 221 a, the first storage electrodes 231, and the gate padmetals 241.

Thereafter, island-type stack structures, obtained by stacking theamorphous silicon layer 223 a and the impurity layer 223 b, to cover thegate electrodes 221 a are formed on the gate insulating film 227.

As shown in FIG. 4C, the source electrodes 224 a and the drainelectrodes 224 b, which are separated from each other on the impuritylayer 223 b, second storage capacitors 224 c, and date pad electrodes232 in date pad regions are formed by depositing Mo, Cu/Ti alloy, orMo/AlNd/Mo on the gate insulating film 227 including the amorphoussilicon layer 223 a and the impurity layer 223 b, and then selectivelyremoving the obtained layer. Here, the drain electrodes 224 b and thesecond storage capacitors 224 may be formed integrally.

Thereafter, the impurity layer 223 b between the source electrodes 224 aand the drain electrodes 224 b is removed, thereby defining channels ofthe semiconductor layer 223. Here, while a part of the thickness of theimpurity layer 223 b is removed, overetching of the amorphous siliconlayer 223 a is carried out and thus a part of the thickness of theamorphous silicon layer 223 a is removed. A structure obtained, asdescribed above, by stacking the amorphous silicon layer 223 a and theimpurity layer 223 b is the semiconductor layer 223.

Thereafter, as shown in FIG. 4D, the passivation film 228 is formed overthe entire surface of the gate insulating film 227 including the sourceand drain electrodes 224 a and 224 b and the second storage capacitors224, first contact holes 228 a to partially exposure the upper surfacesof the drain electrodes 224 b and third contact holes 228 c to exposethe data pad electrodes 232 are formed by selectively removing thepassivation film 228, and second contact holes 228 b to expose the gatepad electrodes 241 are formed by selectively removing the passivationfilm 228 and the gate insulating film 227.

Thereafter, pixel electrodes 225 connected to the drain electrodes 224b, gate pads 235 connected to the gate pad electrodes 241, and data pads235 connected to the data pad electrodes 232 are formed by depositing atransparent electrode filling the first to third contact holes 228 a,228 b, and 228 c on the passivation film 228 and then selectivelyremoving the transparent electrode. On the other hand, if the alignmentkeys 210 provided at the edge of the TFT array mother substrate 200 areformed in the same layer as the pixel electrodes 225, a stack of thetransparent pixel electrodes 225 and the source and drain electrodes 224a and 224 b or the gate electrodes 221 a formed thereunder is used or Mois further deposited on the transparent pixel electrodes 225, thusallowing the alignment keys 210 to be visible when a color filter layeris formed on the transparent electrode.

FIG. 5 is a plan view illustrating a stripe-type color filter layer inthe color electrophoretic display device in accordance with the presentinvention, and FIGS. 6A and 6B are enlarged plan views respectivelyillustrating examples of the color filter layer of FIG. 5 in accordancewith the first embodiment of the present invention and a modifiedembodiment thereof.

FIG. 5 illustrates a stripe-type color filter layer 450 in the colorelectrophoretic display device in accordance with the first embodimentof the present invention. That is, color filters having the same colorare arranged in the longitudinal direction, and pigment materialscorresponding to the color filters are formed in order of red, green,and blue.

FIG. 6A illustrates the stripe-type color filter layer 450 in accordancewith the first embodiment of the present invention, in which colordroplets 461, 462, and 463 in respective pixel regions 450 a, 450 b, and450 c are disposed at a low density so as to increase a light emissionrate through the electrophoretic layer 350 under the color filter layer450. That is, the color droplets 461, 462, and 463 in the respectivepixel regions 450 a, 450 b, and 450 c are formed in an island type andare separated from each other. If such a color filter layer 450 isprovided, transmission of light emitted from the lower part is increasedand thus high brightness is achieved. The color filter shown in FIG. 6Ais referred to as an island type.

FIG. 6B illustrates a color filter layer 455 in accordance with amodified embodiment of the first embodiment of the present invention, inwhich color droplets 464, 465, and 466 in respective pixel regions 455a, 455 b, and 455 c are overlapped with each other.

Although the color filter layer 455 in FIG. 6B has lower brightness thanthat of the color filter layer 450 in FIG. 6A because the color filterlayer 455 in FIG. 6B has higher density of the color droplets 464, 465,and 466 than that of the color droplets 461, 462, and 463 of the colorfilter layer 450 in FIG. 6A, the color filter layer 455 has a high colorreproduction ratio and excellent color sense. The color filter shown inFIG. 6B is referred to as an overlap type.

In any one of the color filter layers in accordance with the firstembodiment or the modified embodiment thereof, during the ink-jetdotting of the respective color droplets, a dotting region must notexceed each pixel region, and color bleeding must be prevented. In theabove embodiments, since the color filter layer is formed afterhydrophobic treatment is carried out on the rear surface (surface onwhich the micro capsule layer is not formed) of the electrophoreticlayer, the droplets of the pigments during dotting do not move andremain in dotted positions, thus being capable of displaying colors.

The island-type color filter and the overlap-type color filter may beseparately applied, or may be combined, if necessary.

Hereinafter, with reference to the accompanying drawings, formation ofthe color filter layer of the color electrophoretic display device inaccordance with the present invention will be described.

FIGS. 7A to 7C are longitudinal-sectional views illustrating a methodfor forming the color filter layer of the color electrophoretic displaydevice in accordance with the present invention.

First, as shown in FIG. 7A, hydrophobic treatment using gas of any oneof SF₆ and CF₄ or a combination thereof is carried out on a surface ofthe substrate 300, on which the micro capsule layer 310 is not formed.

By means of such hydrophobic treatment, hydrophilic color pigmentsdotted are not mixed with each other, and remain in a droplet state.

As shown in FIG. 7B, color droplets expressing a plurality of colors aresprayed onto the substrate 300, on which the hydrophobic treatment wascarried out, through a nozzle of an ink-jet printing device, and therebyeach of the color droplets 460 a, 460 b, and 460 c, expressing onecolor, is formed in one pixel region. In this case, dotting of the red,green, blue color droplets may be simultaneously carried out incorresponding regions, or may be respectively carried out throughseparate processes. From the viewpoint of process characteristics of thepresent invention, the former method is preferable.

Thereafter, hardening is carried out by applying heat so as to allow thecolor droplets 460 a, 460 b, and 460 c to stably remain. In this case,pigments used to form the color droplets 460 a, 460 b, and 460 c may bepigments, which are capable of being hardened by heat.

Thereafter, as shown in FIG. 7C, a protective sheet 400 for protectionmay be further formed on the hardened color filter layer 450: 450 a, 450b, and 450 c.

On the other hand, the hydrophobic treatment may be carried out usingsurface roughness and hydrophobic properties of an adhesive layer (notshown) formed on the surface of the substrate 300, on which the microcapsule layer 310 is not formed, instead of the above-described plasmatreatment using SF₆ or CF₄ gas.

In this case, after the formation of the adhesive layer, color dropletsexpressing a plurality of colors may be prepared above the adhesivelayer and then be sprayed onto the adhesive layer such that each of thecolor droplets, expressing one color, is formed in one pixel region.Thereafter, the same hardening process may be carried out.

Sealing between the side surface of the electrophoretic layer 350 andthe TFT array mother substrate 200 may be carried out using a sealant toprevent the influence of humidity and outside air on the side surface ofthe electrophoretic layer 350. The sealing may be achieved by drawingthe sealant at the outside of the electrophoretic layer 350 or on theTFT array mother substrate 300 prior to bonding the electrophoreticlayer 350 and the TFT array mother substrate 300, and then bonding theelectrophoretic layer 350 and the TFT array mother substrate 300 to eachother.

The color droplets may be formed in the island type, the overlap type,or the island-overlap combination type by adjusting the amount of thecolor droplets sprayed onto each of the respective pixel regions.

FIGS. 8A to 8C are plan views illustrating a process for manufacturing acolor electrophoretic display device in accordance with a secondembodiment of the present invention.

The process in accordance with the second embodiment is nearly identicalwith that in accordance with the first embodiment except that the colorfilter layer 450 in accordance with the second embodiment is formed in aquad type instead of the stripe type.

Here, reference numerals 206 and 207 in FIG. 8A represent a gate padregion and a data pad region, respectively, and from FIG. 8B, it isapparent that the substrate 300 of the electrophoretic layer 350 has anarea which is slightly overlapped with the pad regions 206 and 207.

FIG. 8C shows scribing lines, along which the TFT array mother substrate200 is cut into unit panels. Here, the alignment keys 210 may be placedin a region which is removed by the scribing process, or may remain atthe outside (a part except for the display region) of the unit panel.

A seal pattern to prevent humidity transfer may be further formed at theedge of a surface of the color filter layer 450 or the substrate 300 ofthe electrophoretic layer 350, which is opposite to the TFT array mothersubstrate 200.

Further, non-described reference numeral 260 represents lines, alongwhich the TFT array mother substrate 200 is cut into unit panels,corresponding to the scribing lines. Although FIGS. 8A to 8C illustrateone unit panel as being located in the TFT array mother substrate 200, aplurality of unit panels may be arranged in the TFT array mothersubstrate, and these unit panels are cut along the scribing lines.

FIG. 9 is a plan view illustrating a quad-type color filter layer in thecolor electrophoretic display device in accordance with the presentinvention, and FIGS. 10A ad 10B are enlarged plan views respectivelyillustrating examples of the color filter layer of FIG. 9 in accordancewith the second embodiment of the present invention and a modifiedembodiment thereof.

FIG. 9 illustrates that red, green, blue, and white color filters aresequentially formed in four pixel regions defined to have two pixels inthe horizontal direction and two pixels in the vertical directions.Here, the order of the color filters may be changed, and the white colorfilter may be formed by filling the corresponding pixel with a whitepigment or a transparent organic film or by emptying the correspondingpixel. Here, the case in which the white color filter is formed byemptying the corresponding pixel will be described.

FIG. 10A illustrates the quad-type color filter layer 550 in accordancewith the second embodiment of the present invention, in which colordroplets in R, G, and B pixel regions 550 a, 550 b, and 550 c aredisposed at a low density so as to increase a light emission ratethrough the electrophoretic layer 350 under the color filter layer 550.That is, the color droplets in the respective pixel regions 550 a, 550b, and 550 c are formed in an island type and are separated from eachother. If such a color filter layer 550 is provided, transmission oflight emitted from the lower part is increased and thus high brightnessis achieved. The color filter shown in FIG. 10A is referred to as theisland type.

FIG. 10B illustrates a color filter layer 555 in accordance with amodified embodiment of the second embodiment of the present invention,in which color droplets in respective pixel regions 555 a, 555 b, and555 c are overlapped with each other.

Although the color filter layer 555 in FIG. 10B has lower brightnessthan that of the color filter layer 550 in FIG. 10A because the colorfilter layer 555 in FIG. 6B has higher density of the color dropletsthan that of the color droplets of the color filter layer 550 in FIG.6A, the color filter layer 555 has a high color reproduction ratio andexcellent color sense. The color filter shown in FIG. 10B is referred toas the overlap type.

In any one of the color filter layers in accordance with the secondembodiment or the modified embodiment thereof, during the ink-jetdotting of the respective color droplets, a dotting region must notexceed each pixel region, and color bleeding must be prevented. In theabove embodiments, since the color filter layer is formed afterhydrophobic treatment is carried out on the rear surface (surface onwhich the micro capsule layer is not formed) of the electrophoreticlayer, the droplets of the pigments during dotting do not move andremain in dotted positions, thus being capable of displaying colors.

The island-type color filter and the overlap-type color filter may beseparately applied, or may be combined, if necessary.

FIGS. 11A to 11C are photographs of droplets observed after formation ofthe color filter layer in the color electrophoretic display device inaccordance with the present invention.

FIGS. 11A to 11C are photographs of the droplets of the color filterlayer formed after hydrophobic treatment, which are gradually enlarged.That is, it is observed that the droplets of pigments do not exceedpixel regions and remain in dotted positions, and thus it is understoodthat the island-type or overlap-type color droplets may be freely formedinto the stripe-type or quad-type color filter.

As described above, the color electrophoretic display device includesthe TFT array substrate 200 including a display region 250, in which aplurality of pixel regions are defined in a matrix, and alignment keysprovided at the outside of the display region, the electrophoretic layer350 including the micro capsule layer 310 formed corresponding to thedisplay region 250 of the TFT array substrate 200, and the color filterlayer including a plurality of color droplets formed on a surface of theelectrophoretic layer 350, on which the micro capsule layer 310 is notformed, corresponding to the respective pixel regions of the displayregion 250.

The above-described color electrophoretic display device and method formanufacturing the same in accordance with the present invention has thefollowing effects.

First, a color filter layer is formed on a surface of an electrophoreticlayer after hydrophobic treatment is carried out on the surface of theelectrophoretic layer, and thus droplets forming color filters remainintact in pixel regions, thereby being capable of omitting a partitionto divide the respective pixel regions from each other.

Second, the color filter layer is formed on the electrophoretic layer bydotting pigments in an ink-jet method using alignment keys on a TFTarray substrate under the electrophoretic layer, and thus a bondingprocess between the color filter layer and the electrophoretic layer isnot required, thereby preventing yield lowering due to misalignment.

Third, the color filter layer including the color filters expressing aplurality of colors, i.e., three colors, four colors, or more, may beformed in the ink-jet method using hydrophobic properties of the surfaceof the electrophoretic layer.

Fourth, a process is simplified by the above effects, and an adhesivelayer and a SUS layer are omitted, thereby improving yield and cuttingdown on expenses, and thus improving productivity.

It will be apparent to those skilled in the art that various modifiedembodiments and variations can be made in the present invention withoutdeparting from the spirit or scope of the inventions. Thus, it isintended that the present invention covers the modified embodiments andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method for manufacturing a color electrophoretic display device themethod, comprising: forming a thin film transistor (TFT) array substrateincluding a display region, wherein a plurality of pixel regions isdefined in a matrix, and alignment keys are provided at the outside ofthe display region; forming an electrophoretic layer including asubstrate and a micro capsule layer formed on the substrate so as tocorrespond to the display region of the TFT array substrate; and forminga color filter layer with color droplets expressing a plurality ofcolors on an outer surface of the substrate, on which the micro capsulelayer is not formed, using the alignment keys on the thin filmtransistor array substrate so as to correspond to the respective pixelregions of the display region.
 2. The method according to claim 1,wherein the formation of the color filter layer includes: forming anadhesive layer on the outer surface of the substrate; and preparing thecolor droplets, and then spraying the color droplets onto the adhesivelayer using surface roughness of the adhesive layer such that colordroplets expressing one color are formed in one pixel region.
 3. Themethod according to claim 2, further comprising: after the formation ofthe color droplets expressing one color in one pixel region, hardeningthe color droplets by applying heat to the color droplets.
 4. The methodaccording to claim 2, further comprising: forming a protective sheet onthe color droplets.
 5. The method according to claim 2, furthercomprising: sealing a side of the electrophoretic layer.
 6. The methodaccording to claim 2, wherein the color droplets are formed in an islandtype, an overlap type, or an island-overlap combination type byadjusting the amount of the color droplets formed in the respectiveregions.
 7. The method according to claim 1, wherein the color filterlayer is formed in a stripe type of red, green, and blue color filters,or is formed in a quad type of red, green, blue, and white colorfilters.